METAMOEPHOSES OF ENTOMOSTEACA. 



421 



the adult, but with antennae and feet smaller and more slender than in 

 the perfectly mature state. After two other changes of skin they become 

 capable of reproduction. 



Fig. 216. 



Fig. 217. 



Metamorphoses ofArtemia. 



(1079.) The Salt-marsh Shrimp (Artemia salinus) affords a good ex- 

 ample of these remarkable exuviations. This animal is especially in- 

 teresting, as being, perhaps, the nearest approach in existing nature to 

 the extinct forms of Trilobites so abundantly met with in certain geo- 

 logical strata ; and we have accordingly given, upon an enlarged scale, 

 accurate drawings of its external organization, both in the male and 

 female (figs. 213 & 214). Who, however, would recognize, in the em- 

 bryo of this Crustacean on its first quitting the egg (fig. 215), any re- 

 semblance to the adult creature, or even, in its second condition (figs. 216 

 & 217), be able to identify it as belonging to the same species as that 

 depicted above so completely are all its parts remodelled in their 

 structure before arriving at the mature state ? 



(1080.) EPIZOA. An extensive group of animals closely resembling 

 the Crustaceans have been so constructed as to be capable of attaching 

 themselves to the external parts of other creatures, from which they 

 suck the nourishment suited to their nature. 



(1081.) These parasites are commonly found to infest fishes and 

 other inhabitants of fresh and salt water, generally fixing themselves 

 in positions where an abundant supply of animal juices can be readily 



